guys i need help my root password not working anymore but in terminal i can use roots password but in my GUI i can't how this things happen??

login as a regular user, then type su <enter> then root's password.

It's set up that way for security purposes.

i already do that , i want to install a antivirus but in GUI requires a administrative rights which is root but i try to enter my password it doesn't work , but in my black screen which is a command prompt in windows my roots password works well what shall i do sir..

specifically which distro are you using?

I expect you are using an ubuntu based distro, and your antivirus has a gui-based installer?

Use "kdesu" or the gnome equivalent (depending on your desktop environment) instead of su. The root user may not have access to your x window. However if you run a console program such as "rpm" to install the package in the terminal, then "sudo" will be fine. Some distro's also have a "sux" program to do the same thing.

What kind of antivirus program are you trying to install? There is an antivirus program that scans for windows viruses if you are running a mail server or file server. Otherwise you might by getting snookered or even be trying to install something that claims to be an antivirus program but actually installs a root kit.

Please put your distro in your user profile. Also indicate the name of the package. Then we can tell you the "apt-get" or "zypper" command to run to install a package.

Also, try to use your package system to install packages. Especially as you are new to Linux. You will have fewer problems that way, as dependencies will be installed as well and the versions of libraries will match up.

sorry sir i forgot to post my distro Im using mandriva 2007 and i just want to download from its software a anti virus but it requires a roots password i tried to enter many times but password incorrect but actually i used root's password in entering a command prompt that black screen and it works how come that may roots password works in command prompt and it doesn't work in my GUI when it requires a password sir.

Are you trying to do this through rpmdrake? Are you a member of the "wheel" group. One thing that could cause a problem is if your character encoding maps an oddball character differently than root's encoding. I'm still not straight on whether your problem is with the password being rejected or if the root user is denied access to the desktop.

If you can't install it through rpmdrake, you could try using urpmi in the console instead.